<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        span{
            color: red;
        }
        .chao{
            color: green;
        }
        #ID_selector{
            color: blue;
        }
        h4,h5{
            color: yellow;
        }
    </style>
    <link rel="stylesheet" href="position.css">
<link rel="stylesheet" href="../html/selector.css">
<link rel="stylesheet" href="background.css">
<link rel="stylesheet" href="Float.css">
</head>
<body>
<h1>Hello World<span>span是这样用的</span></h1>
<h2 class="chao">超类</h2>
<h3 id="ID_selector">id选择器</h3>
<h4>合并</h4>
<h5>选择器</h5>
<p>元素选择权重1</p>
<p>class选择器权重为10</p>
<p>id选择器权重为100</p>
<p>内联样式权重为1000</p>
<!--背景颜色-->
<div id="background"></div>
<div id="background2"></div></body>
<!--浮动-->
<div id="float">
    <img src="images/sights.jpeg" alt="">
    <img src="images/scenery.jpeg" alt="">
</div>
<div id="float2"></div>
<div id="float3"></div>
<div class="position"></div>
</html>